Radio frequency transformer



July 9, 1929. R. w. OSBORNE j 1.719.995

RADIO FREQUENCY TRANSFORMER Filed Dec. 27, 1927 2 Sheets-Sheet l July 9, 192 9. w, QSBQRNE I 1.719.995

RADIO FREQUENCY TRANSFORMER Filed Dec. 2 v Q'Shets-Sheet vwv\ 3 30 38 is r 5:5 4/ 42 55 -13 (if PM 1 I H 7 "Hum t m Patented July 9, 1929.

RALPH WILLO'UGI-IBY OSBORNE, OF TORONTO, ONTARIO, CANADA,

RADIO FREQUENCY TRANSFORMER.

Application filed December 27, 1927. Serial No. 242,671

My invention relates to improved types of radio frequency transformers for use as input and outputtransformers of radio frequency amplifiers, radio frequency generators and the like, and for interstage trans formers or couplers in cascade radio frequency amplifiers in radio transmitting and receiving apparatus, or for the transformation of any high frequency energy where electro-statio coupling between the windings of the'transformer is detrimental to the efficiency of transformation.

To those familiar with the art, it is well known that the electro-motive forces of electro-static and electro-magnetic induction cause currents to flow respectively which are.

in phase opposition to each other and that in radio-frequency transformers, a very small electro-static capacity between the windingsmay cause an appreciable transfer of energy from the primary winding to the secondary winding by electro-static induction in opposition to the energy transferred by electromagnetic induction, thus reducing the efficiency of transformation, unless in the designing of the transformer care is taken to so arrange the windings that the effect of electro-static induction between windings is minimized.

The object of my invention is to provide a type of radio frequency transformer wherein the effect of electro-static induction between windings, as opposed to electromagnetic induction, is zero.

To attain this object I provide a radio frequency transformer with primary and secondary windings so, arranged and inter related that when energized, the electro-' static flux emanating from either WIIIdIHg' induces in the other winding equal and opposite components of electro-motive forces whose resultant difference of potential between the extremities of the said other winding is zero, while the electro-magnetic flux emanating from either winding induces in the other winding electro-motive forces which are cumulative. The attainment of this object as above stated is made possible due to the fact that when an object such as a wire is electrified, the electro-static flux emanates from the wire radially and is a function of the voltage at which the wire is charged, while the electro-magnetic flux encircles the wire and is a function of the current flowing in or along the wire; wherein the diiference'in the behaviour of the two forms of flux makes it possible to eliminate the effects of one Without interfering with the effects of the other.

In order to understand my invention more fully referencemay be had to the following description and accompanying drawings illustrating a form of my invention, in which- Figs. 1,1, l and 2, 2* are end and side elevations respectively, Figs. 3 and 4 two types of radio receiving circuits illustrating more clearly how my invention may be adapted lJO'fHIlCtlOII in various types of circuits and in different parts of a given type of circuit.

Referring to the drawings it will be noted that in Figs. 1, 1 and 1 I have shown a radio frequency transformer having a pri-' mary winding 11 in two halves 1 and 2 as indicated, respectively, by the lightly shaded and heavily shaded strands, wound about an even number of spokes in a radial plane at right angles to the axis of a secondary winding 5 wound in two halves 3 and 4 in cylindrical form. In winding the primary winding 11 it will be noted that the darkly shaded strand 2 is started at terminal 6 and Wound in a counterclock-wise direction and woven in and out about the spokes for a half turn to point 7, then the lightly shaded strand 1 is started at terminal 6 and wound in a clock-wise direction and wound in and out about, the spokesuntil it crosses strand 2 at point 7 then strand 2 is continued to point 8 and strand 1 is continued until it crosses strand 2 at point 8, the process continuing in this order until the winding is completed at terminals 9 and 10. Upon close examination it will be seen that strands 1 and 2 occupy similar positions for equal distances throughout their length with reference to the secondary winding 5 or other I objects in their vicinity. When the primary winding 11 is energized strands l and 2 assume, respectively, equal and opposite potentials with reference to the neutral point 6, and the electro-static flux emanating from strand 1 will be equal to, and of opposite polarity to that emanating from strand 2, so that equal components of electrostatic flux of opposite polarity will radiate from the primary winding 11 to the secondary winding 5 and the resultant potential induced thereby will be zero; while the electro-magnetic flux due to current flowing in transformer, it may Fig. l shows the primarywinding 11 centrally located with reference to the secondary winding 5,, it is advantageous for some purposes to locate the primary winding at one end of the secondary w nding as shown at 11 n Fig. 1. I

I If conditions are the reverse of the above description, that, is to say if the cylindrical winding the pri'mary winding and is energized the electro-static flux emanating from the cylindrical winding 5 willimpinge equally upon strands 1 and 2 of the other winding 11 inducing equal potentials of the same polarity in strands 1 and 2, thus causing no difference of potential between the terminals 9 and 10; while the electro-magnet-1c flux encircling the turns of the cylindrical. winding will also encircle strands 1 and.2 of the other winding thus inducing potentials which are cumulative and result in a/difference of potential between terminals 9and 10 of winding 11. A trans.

- former constructed in this form is used as an interstage transformer as indicated at 22 in Fig. 3 of the drawings.

As will be evldentwvhen further description discloses the var ous adaptations of my be constructed in various form's without departing from the basic principle employed to attain the object of myinvention.

.When the primary winding 11 is the 1 form already described. and is centrally 1'0- rudiment...

cated with reference to the secondary winding 5 as indicated in Fig. 1 the secondary winding 5 is divided into two halves 3 and 4 the terminals 12 and 13 being. joined together to form a neutral point. When the primary winding is placed at the end of the secondary winding as indicated at 11 in Fig. 1", thesecondary winding 5 is usually wound in a single section havingno neutral point.

'A transformer constructed in thisform is used as an output transformer as indicated at 29, in Fig; 3 and at 4:9 in Fig. 4C. a

:In Figs. 2 and 2 the primary winding is constructed. of I a single conductor wound about an odd number of spokes andcentrally located with reference to the secondary winding 5 in Fig. 2; In this form it will be similar in appearance to the transformer as indicated 1n Fig;

' primary. winding i 4 being located in the same relative position as the primary winding 11 reversed, that is to say,

.51, the single conductor previously described. The terminals 12' and 13 of the two halves 3 and 4: of the secondary winding 5 are joined together to form a neutral point. The primary winding 11 being equidistant from the several turns respectively of each half 3 and 4 of the secondary winding 5 so that when the primary winding is energized, the electro-static flux emanating from the primary winding will be impinged equally and at the same polarity on the several turns of each half 3 and i respectively of the secondary winding 5,, causing no difference of potential at the terminals 1 1" and 15' of the secondary winding 5, while the .electro-magnetic flux set up around the primary winding will encircle thetwo halves 3 and 1 of the secondary winding 5' inducing potentials which are cumulative... A transformer constructed in this form is used as an input transformer as indicated at 18in Fig. 3 ofthe drawings. If in this type of transformer conditions are Y if the cylindrical winding 5 used as a primary windin and the single conductor winding wound about the odd number of spokes centrally located with reference to the cylindrical winding 5", is the secondary winding, it may be used as an' output transformer as indicated at 29 in Fig. 3 and at 49 in Fig. 4 of the drawings, v

Fig. 3 of the drawing, is a diagrammatic view of a radio receiving apparatus employing a cascade radio frequency amplifier of the balanced or push-pull type in which 16 isthe antennae, 18 is the input radio frequency transformer of which 17 is the primary winding, comprising a single con-ductorwound upon an odd number of radial spokes and centrally located with reference to the secondary winding wound in cylindrical form in two halves 19 and 20, said secondary winding having its neutral point 21 connected to ground by means of ground wire 42, the extremities of said secondary winding being connected respectively to the grids of the amplifying tubes 37 and 38. 22is an interstage transformer of the form indicated in Figs. 1 and .1 in which ex tremities 23 and 21 correspond respectively to terminals9 and 10 inFig. 1 and are conne'cted respectively in the plate circuits of amplifying tubes 37 and 3-8, the neutral point 25 corresponding to terminal '6 in Fig. 1 being connected to a source of battery supply B by means of wire 13. 27 and 28 are the two halves of the secondary winding corresponding respectively to the two halves 3 and 4, of the secondary winding 5 in Fig. 1 the extremities of which are connectedrespectively to the grids of the amy plifying tubes 39 and 40, 2 6 is the neutral point formed by joining terminals 12 and '13 in Fig; 1*, connected to ground by means of wire 11 and secondary winding 35 0f audio min frequency transformer 34 29 is the output transformer in which and 31 of the primary winding correspond respectively to terminals 9 and 10 in Fig. 1 and are connected respectively in the plate circuits of the amplifying tubes 39 and 40, the neutral point 32 corresponding to terminal 6 in Fig. 1 being connected to a source of battery supply B through wire 45 and reproducing device 46, and 33 the secondary winding wound in asingle section and having the primary winding located at one end'as indicated at 11 in Fig. 1' Secondary winding 33 delivers the amplified radio fre 3 quency energy to the detector tube 41. In

order to illustrate further advantages to be gained by theme of my radio frequency transformer, I have shown how the signals may be delivered from the detector 41 to the primary winding 36 of the audio frequency transformer 34, thence from the secondary Winding to the neutral point 26 of the secondary winding of the radio frequency transformer 22 by means of wire 44, dividing at'the neutral point 26 through each half 27 and 28 of the secondary wind ing of the radio frequency transformer 22 to the grids of the amplifying tubes 39 and 40, and how the amplified audio frequency energy is delivered from the plates of amplifying tubes 39 and through the two halves of the primary winding of radio frequency transformer 29 to neutral point 32 thence by means of wire to the reproduc- 1 ing device 46. The amplifying tubes 39 and 40 thus amplify the radio frequency and audio frequency energy simultaneously without interference between the two frequencies because the electrodes of the tubes 39 and 40 are respectively at opposite polarities with reference to the radio frequency energy, while they are at the same polarity with reference to the audio frequency en ergy.

I have shown how my invention may be adapted to the balanced or push-pull type of radio-frequency amplifier. When used in this manner it operates in a more satisfactory manner than the conventional types of radio frequency transformers heretofore in use, because of its higher efficiency, less tendency to go into self oscillation and comparative freedom from outside interference and static. My invention may also be adapted to the one tube per stage type of amplifier as indicated in Fig. 4 of the drawings in which 47 is the antennae, 48 a conventional type of input transformer delivering energy to the grid circuit of amplifying tube 54, 49 is an adaptation of my transformer as an output transformer with one extremity 50 of the primary winding connected in the plate circuit of the amplifying tube 54 while the other extremity 51 is connected to the grid of the tube through balancing condenser 57.

WVhile I have shown and described one embodiment of my invention and various adaptations thereof, .it will be understood that various modifications in form and construction of its component parts may be made without departing from the spirit and scope of the appended claims.

WVhat I claim is:

1. A radio-frequency transformer comprising a winding wound in cylindrical form and a-winding wound on a support in a radial plane fixed at an angle with the axis of the said winding wound in cylindrical form and having a neutral point, the successive turns on either side of the said neutral point being transposed at intervals so that when energized all parts of the said winding wound on a support in a radial plane that are at equal and opposite potentials are equidistant from the winding wound in cylindrical form.

2. A radio-frequency transformer comprising a winding wound in cylindrical form and having a neutral pointand a winding Wound on a support in a radial plane fixed at an angle with the axis of, and coincident with the neutral zone of the said winding Wound in cylindrical form, said winding wound on a radial support having a neutral point, the successive turns on either side of the neutral point being transposed at in tervals so that when energized all parts of each winding that are at equal and opposite potentials are equi-distant from the other Winding.

3. A radio-frequency transformer comprising a winding wound in cylindrical form and having a neutral point connected to a terminal, a number of radial spokes set in a radial plane at right angles to the axis of, and coincident with the neutral zone of the said winding wound in cylindrical form and a winding wound in spider-web form about the said radial spokes.

4. A radio-frequency transformer comprising a winding wound in cylindrical form, an even number of radial spokes set in a radial planeat right angles to the axis of the said winding wound in cylindrical form, a winding wound in spider-web form about the said radial spokes, said winding being in two halves and having a neutral point, the individual turns of each half being wound alternately, one in a clock-wise and the other in a counter-clock-wise direction, crossing and recrossing between the spokes, the said two halves of the winding being joined in series relation, the junction being the neutral point Which is connected to a terminal.

5. A radio-frequency transformer comprising a winding Wound in cylindrical form and having a neutral point connected to a terminal, an even number of radial spokes set in a radial plane at right angles to the axis of, and coincident with the neutral zone of the said winding wound in cylindrical form, a winding wound in spider-web form about the said radial spokes, said winding being in two halves and having a neutral point the individual turns ofeach half being wound alternately, one in a clock-wise and the other in a counter-clock-wise direction, crossing and recrossing between the spokes, the said two halves of the winding being joined in series relation, the junction being the neutral point which is connected to a terminal. i

6. A radio-frequency transformer comprising a winding having a neutral point and another windmg in electro-magnetic inductive relation thereto, each successive turn on either side of the neutral point of said winding having a neutral point so positioned in, equidistant relation to each successive turn of the said other winding in electro-magnetic inductive relation thereto, that when the said transformer is energized the electrostatic flux emanating from either winding induces in. the other winding an even distribution of electrostatic charges causing no resultant diiference of potential between the extremities of the said other winding, while the electromagnetic flux emanating from either winding induces in the other winding electromotive' forces which are cumulative.

7. A radio-frequency transformer comprising a winding wound in cylindrical form and having a neutral point, and a winding wound on a support in a radial plane fixed at an angle with the axis of and coincident with the neutral zone of the said winding wound in cylindrical form so that when energized all parts of the said winding wound in cylindrical form that are at equal and opposite potentials are equidistant from the winding wound on a support in a radial plane.

y In testimony whereof I affix my signature this twenty-first day of December at the city of Toronto.

RALPH VILLOUGHBY OSBORNE. 

